RE: Serpent lake ,Crosby
I haven't been on the lake for some time, but grew up in the area and fished it a few times. Serpent is a very clear lake that typically produces a lot of fish on jigs and rigs. Occasionally you can get some 'eyes throwing cranks up over the weed tops, but that's usually a low light/night time bite. Historically trolling boards and cranks proabably isn't going to cut it because of the drop offs. You may be able to do some precision trolling along the dropoffs and weed edges, but I've typically stuck with the basic live bait stuff.
Hope that gets you started.